RE: gas/air question

["Pavel Tcholakov" <pavel@xxxxxxxxx>]

For what it's worth, I'm driving with nitrogen in my tyres. I'm not sure
why not CO2, but as you all know athmospheric air consists of mostly
nitrogen (around 70%), oxygen (around 10%), CO2, other inert gasses and
lots of impurities. Apparently, nitrogen has a much better temperature
expansion curve thus pressure stays relatively more stable and tyres do
not build up as much heat. Also, I only have to go top up once every 3
months as nitrogen doesn't leak through the tyre sidewalls as the
smaller molecules of oxygen do. I don't see a problem with CO2 from this
point of view, but perhaps temp expansion is different? That's the only
thing that could be harmful as any major temp fluctuations will cause
your tyres to flex more and will wear them out quicker, excessive heat
could even cause blowouts. Formula 1 and aircraft are said to have their
tyres inflated with nitrogen, so why not. Plus they give you cool green
valve caps! ;-)

P.

-----Original Message-----
From: owner-bmw@domain.elided [mailto:owner-bmw@domain.elided] On Behalf Of
Tdb1946@domain.elided
Sent: Thursday, July 17, 2003 8:27 PM
To: bmw-digest@domain.elided
Subject: gas/air question


Recently my air compressor went south and I needed to adjust tire air 
pressure. I have a CO2 cylinder for welding. have wondered if it would
be harmfull to 
use carbon dioxide to add a few lbs in a tire otherwise filled with air.

Would the gas/air in such a tire expand faster/slower than just air? Any
harm to 
the rubber? Speaking of  tires on BMW's only of course! Thanks for any
info, 
opinions.
Tom
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